The invention relates to a watch strap provided with a catch, particularly an articulated watch strap in which the links and the catch parts are interconnected by hinge joints.
Numerous types of watch straps of this kind are known from prior art, which are provided with a two-piece catch designed in such a manner that one catch piece serves as a receptacle for the other catch part. In one or the other catch part an interlocking mechanism is installed.
In the German Pat. No. 1,170,183 a two-piece catch is described in which the receiving part has a U-shaped cross section and is provided with a longer arm at the intermediate range of which a knob-like suspension member is attached for engaging a recess in the other part. The catch mechanism is provided with an interlocking device consisting of a sleeve in which a threaded pin provided at its outer end with a transverse latch, is screwed with friction. In the completely screwed in position of the threaded pin the transverse catch is situated above the two interlocked catch parts.
Another embodiment of catch mechanisms described in this patent is provided with a shiftable latch which engages by means of a tongue the lower part of the knob-like suspension member.
From the German Pat. No. 1,557,440 a catch is known wherein one catch part is provided with a pin insertable in transverse direction to the length of the strap into a bore in the other catch part. A turnable arm provided with a pressure knob and with a rib snaps with the latter in a groove in the first catch part and is arrested in the closing position by an additional pin and bore connection.
Furthermore, from the Swiss Pat. Nos. 563,742 and 563,743 catches are known with which one of the catch parts is provided with a hook-shaped suspension part which is introduced in an aperture in the other catch part where it is hooked up. A rotary bolt provided with a little semicircular plate or a nose is arranged in the interior of the receiving catch part. By rotating this bolt, the little plate or the nose is shifted over the suspension part and ensures the latter against dropping out.
The constructions of the prior-art catches of this kind are very complex and hence expensive in manufacture. In addition, the insertion of the suspended part in the receiving catch part in the looped watch strap is difficult, inasmuch as the suspension part must be guided with minimum play behind the knob-like suspension member, or the pin must be guided in a narrow bore, or the hook-shaped suspension part must be inserted in a narrow gap in the receiving catch member. In order to open or close the locking mechanism in the prior-art catch devices according to the aforedescribed Swiss patents, there is necessary an additional auxiliary means such as a coin or the like. Moreover, the prior art catch parts have a completely different configuration than the links of the strap, so that they contrast with the latter and do not form a harmonious unit with the watch strap.
In watch straps of the aforedescribed kind, the strap links and the catch parts are usually interconnected by hinge joints. For this purpose, there are employed hinge tubes which are secured to the strap links and to the catch parts by soldering. Due to the minute dimensions of hinge tubes, whose size in temporary superflat strap links still decreases, the soldering process encounters many problems. For example, it is very difficult to apply the correct amount of solder. When too much solder is applied, then the excess rushes out, and the passages must be cleaned in an aftertreatment process. If, on the other hand, too little solder is applied, the hinge tubes are prone to disconnect easily from the links or catch parts when subject to loading. In addition, care must be taken that the solder is uniformly distributed over the entire surface to be soldered, so that the hinge tubes be not attached to the assigned link or catch part at an oblique angle.
Due to high temperatures resulting during the soldering process, the metal of the strap links or catch parts, as well as the hinge tubes themselves, become decolorized in the range of the soldering point, and consequently a further mechanical or galvanic aftertreatment is necessary.
Since sheet or rolled gold is qualitatively better and has also a better wearing quality than a galvanically applied gold layer, it is preferred in the trade to use articulated watch straps or bands whose links and catch parts are provided on its upper side with a rolled gold coating. In soldering hinge tubes on such strap links, there again appears the problem of discoloration due to high soldering temperature. Since the rolled gold coating is provided only on the upper side of the strap links and catch parts, while the other portions are uncoated, a galvanic aftertreatment for restoring the color of the upper surface is no longer possible, inasmuch as the other portions, which should remain free, would become coated. The method of selective plating for recovering a perfect upper surface would be also inapplicable, because of its considerable cost.
Due to the required precision and precaution during the soldering of hinge tubes to the strap links or catch members and the necessary aftertreatment for cleaning the soldered points the assembly is time-consuming and makes the manufacture of such strap links with catch parts very expensive. The attachment of hinged tubes to the links or catch parts by welding is hitherto impossible.